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authoryuzhoujian <yuzhoujian@didichuxing.com>2018-01-29 10:25:23 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-02-16 10:18:06 -0300
commitf1f8ad52f8bf1239282737a2a5c3bd450300cc78 (patch)
tree825e2343786db8de5a4b9948381ff299c2c094a6 /tools/perf/Documentation
parentdb06a269ecbb1d71d534fc5713624eeeee0b8f92 (diff)
downloadlinux-f1f8ad52f8bf1239282737a2a5c3bd450300cc78.tar.bz2
perf stat: Add support to print counts after a period of time
Introduce a new option to print counts after N milliseconds and update 'perf stat' documentation accordingly. Show below is the output of the new option for perf stat. $ perf stat --time 2000 -e cycles -a Performance counter stats for 'system wide': 157,260,423 cycles 2.003060766 seconds time elapsed We can print the count deltas after N milliseconds with this new introduced option. This option is not supported with "-I" option. In addition, according to Kangliang's patch(19afd10410957), the monitoring overhead for system-wide core event could be very high if the interval-print parameter was below 100ms, and the limitation value is 10ms. So the same warning will be displayed when the time is set between 10ms to 100ms, and the minimal time is limited to 10ms. Users can make a decision according to their spcific cases. Committer notes: This actually stops the workload after the specified time, then prints the counts. So I renamed the option to --timeout and updated the documentation to state that it will not just print the counts after the specified time, but will really stop the 'perf stat' session and print the counts. The rename from 'time' to 'timeout' also fixes the build in systems where 'time' is used by glibc and can't be used as a name of a variable, such as centos:5 and centos:6. Changes since v3: - none. Changes since v2: - modify the time check in __run_perf_stat func to keep some consistency with the workload case. - add the warning when the time is set between 10ms to 100ms. - add the pr_err when the time is set below 10ms. Changes since v1: - none. Signed-off-by: yuzhoujian <yuzhoujian@didichuxing.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Milian Wolff <milian.wolff@kdab.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/1517217923-8302-3-git-send-email-ufo19890607@gmail.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation')
-rw-r--r--tools/perf/Documentation/perf-stat.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 47a21645f60c..2bbe79a50d3c 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -151,6 +151,11 @@ Print count deltas for fixed number of times.
This option should be used together with "-I" option.
example: 'perf stat -I 1000 --interval-count 2 -e cycles -a'
+--timeout msecs::
+Stop the 'perf stat' session and print count deltas after N milliseconds (minimum: 10 ms).
+This option is not supported with the "-I" option.
+ example: 'perf stat --time 2000 -e cycles -a'
+
--metric-only::
Only print computed metrics. Print them in a single line.
Don't show any raw values. Not supported with --per-thread.